Studies on the morphological, crystalline, thermal properties of an under utilized starch from yam Dioscoreae zingiberensis C. H. Wright

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Abstract

Physicochemical properties such as AM content, morphology, gelatinization, crystallography and pasting behavior of an under utilized yam starch from Dioscoreae zingiberensis C.H. Wright were characterized by SEM, particle size analysis, X-ray powder diffraction, DSC, and Brabender viscoamylograph, and compared to commercial potato and maize starches. D. zingiberensis starch had an AM content of 23.62% and exhibited a flattened ovoid shaped granules with majority (87.4%) of them having diameter in the range of 10–50 µm and centering at 21.192 µm. The X-ray powder diffraction showed A-type crystalline patterns of D. zingiberensis. Higher values in onset temperature (To, 70.49°C), peak temperature (Tp, 78.53°C) and conclusion temperature (Tc, 85.96°C) of D. zingiberensis. Unlike potato starch, pasting properties of D. zingiberensis starch were somewhat similar to that of maize starch. Pasting onset temperature, maximum, breakdown, and setback viscosity of D. zingiberensis starch were 73.4°C, 309, 46, and 161 BU, respectively. Interestingly, a very stable paste viscosity was observed during high temperature (5 min for D. zingiberensis starch.

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